One thing I’ve learned since becoming a home owner ~5 years ago… There’s a lot of stuff on the Internet that tries to get you to a point of hysteria.
https://www.premiumwaterproofing.com/wp-content/uploads/2022/04/stairstep-cracks.jpg
https://www.du-west.com/wp-content/uploads/2021/12/bulog1-1920w.jpg
This is the kind of stair step crack you need to worry about. It’s a big gap, many blocks, etc. It’s a sign part of your foundation is sinking.
What you have is a block missing some mortar and a crack below (which can happen if water gets into the block … which happens when you’re missing mortar). You can have someone look at it, but I think an honest contractor would tell you “get it repointed or do it yourself, keep an eye on it.”
You don’t need an epoxy of any sort for this … just a grinder, some more mortar, and a joiner.
This is just something that happens with masonry after decades.