Ok, I see what's confusing here... and I had to go deeper to kind of make sure I could explain it to you. Hopefully I can explain... 🤣

So, what you think you are doing is that by modifying the json_metadata of a specific comment operation, you are affecting the tags of that comment. And you are correct, but only at the L1 tags level of that comment operation.

On L2, because it depends on the DB (aka the previous state of the information) of the L2 previously parsed and verified information, you are effectively inheriting the parent tags (post or comment) for that comment. Effectively, the L2 previous information is overwriting what you think you are overwriting yourself via L1.

This is the part that gets confusing, because when you go check on L1 chain, you think L2 took those values, but instead you have to look at what L2 parsed before and you can see this from the HE DB because the information that will be carried on via the comments contract is the inheritance of the tags since the main post, at whatever level you want from that post. This is not visible (does not respect the same information on L1) in the same way you see L2.

😎 Thanks for making me learn too! LOL - these are the things that make me go verify :D