Maximum amount of “tags” you can use for a single post

Hello Community. Some time ago I was having trouble posting in the various “tag” sites. I was told here that I was using more than four tags when I posted and that was the issue. I stopped doing that and it cleared the issue up for some of my sites but one was having another problem separate from that which was eventually cleared up.

What I was curious about now is if that four “tag” rule is till in effect. Can you use more now and if you can, how many more?

Thank you for your responses.