Problems are easy to find - relation/5371741/history is one. The original relation was tagged as amenity=school but was a type=site relation, you added education=school and someone then removed amenity=school from that and added it to the outer way way/29083822 .
The overpass query to find these problems is https://overpass-turbo.eu/s/2hfT - change the area of that to look elsewhere.

The osm.wiki/Proposal_process page contains the text "Also, a vote result is never permission for large-scale re-tagging of existing objects. See automated Edits code of conduct for more about this topic. " (and osm.wiki/ES:Procedimiento_de_propuesta likewise "Además, nunca utilices el resultado de una votación como justificación para el reetiquetado a gran escala de objetos existentes. Véase el código de conducta de ediciones automatizadas para más detalles sobre este tema. ").
I don't think that a revert will solve the problem, since any iD edits will just force the tag back in, but you will now need to monitor and manage the 20k objects you have edited to check for problems.

(see also comments on changeset/145120734 and changeset/141126341 )

Actually changeset/163106660 (by a different mapper, ages ago) looks odd too.

Hello,
I'm a bit confused by the change here to https://map.atownsend.org.uk/maps/osm-deep-history/#/way/224164207 - the cycleway by the side of the road is now "bicycle=no; foot=no". That seems unlikely?
Best Regards,
Andy

Hola,
Esto parece una edición automatizada. ¿Podrías indicar dónde se discutió con la comunidad?
Atentamente,
Andy
(Nota: este conjunto de cambios se enlazó desde https://community.openstreetmap.org/t/why-is-it-ok-that-id-performs-undiscussed-semiautomatic-distributed-mass-edits/139011/33)

Hello,
This looks very much like an automated edit. Can you point to where it was discussed with the community?
Best Regards,
Andy
(note - this changeset was linked from https://community.openstreetmap.org/t/why-is-it-ok-that-id-performs-undiscussed-semiautomatic-distributed-mass-edits/139011/33 )

Re https://community.openstreetmap.org/t/clarifying-default-bicycle-access-on-highway-footway-and-highway-pedestrian/139023/124 , https://map.atownsend.org.uk/maps/osm-deep-history/#/way/240214608 et al now have "bicycle=dismount; foot=no". I've no idea what is correct but that is an implausible combination (I've also said this on the changeset by the other recent editor).

Re https://community.openstreetmap.org/t/clarifying-default-bicycle-access-on-highway-footway-and-highway-pedestrian/139023/124 , https://map.atownsend.org.uk/maps/osm-deep-history/#/way/240214608 et al now have "bicycle=dismount; foot=no". I've no idea what is correct but that is an implausible combination (I've also said this on the changeset by the other recent editor).

Hello,
I have reverted the changes to the Englist and French names of https://map.atownsend.org.uk/maps/osm-deep-history/#/relation/6646538 in changeset/175899550 .

Hello,
Andy from OSM's Data Working Group here. Please respect each other's names for things - as you can see from https://map.atownsend.org.uk/maps/osm-deep-history/#/way/456788679 there have been numerous deletions by several users, including both of you.
If you continue to do that we will have to prevent you from editing OSM.

Hola Calasanz, soy Andy, del Grupo de Trabajo de Datos de OSM.
Gracias por añadir una imagen de Wikimedia Commons de la señal de calle way/529079441. Como pueden ver en https://map.atownsend.org.uk/maps/osm-deep-history/#/way/529079441, el nombre ha cambiado con el paso de los años.
Sin embargo, sugeriría dejar las versiones "name:ca" y "name:es" si son correctas (que presumiblemente lo son). Tener todos los nombres de idiomas para una calle permite a quienes consultan los datos crear nombres en diferentes idiomas. Si se elimina name:es, no sabrán cuál es el nombre en español, ya que nada define en qué idioma se escribe "name".
Atentamente,

Hello Calasanz,
Andy from OSM's Data Working Group here. Thanks for adding a Wikimedia Commons image of the street sign of way/529079441 . As you can see from https://map.atownsend.org.uk/maps/osm-deep-history/#/way/529079441 , the name has been changed back and forth over the years.
However, I would suggest leaving the "name:ca" and "name:es" versions if they are correct (which they presumably are). Having all of the language names for a street allows people consuming the data to make makes in different languages. If you removing name:es, they won't know what the Spanish name is since nothing defines what language "name" is.
Best Regards,

Hello,
I'm a bit surprised to see that https://map.atownsend.org.uk/maps/osm-deep-history/#/way/829316713 became "bicycle=dismount" here. It's tagged as a public bridleway in OSM, which agrees with the local authority https://map.atownsend.org.uk/maps/map/map.html#19/53.25103/-1.83267/H/P , so I'd expect "bicycle" to be at least "yes". Are there signs discouraging cycling?
Best Regards,
Andy

(in the pouring rain)

@synthfi I suspect that it's forgivable in this case as they're using MAPS.ME to update the details of some airports they flew through - likely they weren't in a position to upload until they got home.

Agreed - "manmade" is pretty obviously a typo for "man_made" here.
Where problems might occur with changes like this is where both "manmade" and "man_made" were set. Here there were only 5 and only node/8322504104/history had them set to plausible different values (although there are only 30 https://taginfo.openstreetmap.org/tags/man_made=scoreboard , and the existence of a subtag suggests the other value).

The obvious precaution is "not to use Google Maps as a source". There's more information at osm.wiki/Google and osm.wiki/FAQ#Why_don't_you_just_use_Google_Maps/whoever_for_your_data? .

Thanks!

You probably haven't got to it yet, but way/403875321/history is also iffy.