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