Sure it's a real thing for memories to surface that were previously buried. It's happened to me.

If it happens in therapy, that doesn't mean the memories are "implanted". And not all memories lack the ability to validate them... for example, if you've forgotten someone's name, then remember it later, you can call out to them by their name to confirm that you've correctly remembered it.

Memories tumble around in the brain all the time, not all memories are easy to access, but that doesn't mean they're inaccessible.

The point that memories can also be implanted or fabricated during therapy is absolutely an important one, but dismissing the possibility for memories to resurface (and conflating any situation where this might happen with a specific type of discredited therapy) is needlessly reductive.