Comment by greazy
9 hours ago
I haven't seen an actual experiment that replicates anecdotal evidence but this discussion comes to mind
https://news.ycombinator.com/item?id=42580659
from memory, the logical explanation is that by connecting to the same wifi the new tracked profile is being used. For example, the grand parent could have been learning Spanish, their profile gets picked up.
Another explanation is observation bias. Spanish ads were shown previously, but were ignored. Now you're on the lookout for them, so they're more noticeable.
No telling how to actually test this but this anecdote is true, and there was absolutely no spanish involved in that household prior. Nobody in that household speaks that language, not even the cuss words.