Doesn't matter. Most email services[1] use it the way Gmail does and spam is a numbers game. Losing a few valid addresses is worth correlating all those other addresses for most spammers.

Standards only matter to nerds like us.

[1] https://proton.me/blog/what-is-email-alias#5

Except plus address users are also less likely to be receptive to spam, so it's probably better to just not bother

Spam has never been about how "receptive" the recipient is.

They can check if it's Gmail though.