Is anyone facing this issue with Google Search Console indexing?

So I have a client's website which gets indexed within minutes but this time it isn't getting indexed even after a couple of hours. Is anyone else facing this issue for their sites with similar circumstances? Like I think yesterday there was a date related bug in GSC as well hence, I wanted to know if indexing too has gotten messed up this time today.

I've encountered similar issues with indexing tools before. Initially, they show a page as indexed, and it even appears on Google. However, after a few days, it suddenly shows as not indexed. It's quite a strange situation.

Update: It got indexed today but still it is quite concerning that a site whose pages get indexed with minutes took more than a few hours. Looking to some answers regarding why this delay in indexing could have happened.