If working on the same ones, then after a few days, yes. By then you should have explored some debugging techniques, options for solution, etc., and either can't figure out how to replicate or debug it or have found a tricky bug and 1-3 ideas for a solution, but all the potential solutions seem bad. That's when you can say you're blocked, ask the team for ideas on how else to replicate/debug, or try to get consensus for the least-worst hacky fix that you've come up with, or any other ideas based on what you've found. We all spin our wheels or get stuck sometimes, so of course we understand, and that's exactly what it's for. But you have to give that context and say where you're stuck.

The problem is that product managers and management in general want features and don't care about technical debt.

So if you are working on a bug (fixing technical debt) then you are not working on a feature.

Also, working on features is often (but not always) more predictable in time estimation than working on bugs, which can be a completely exploratory task with the only endpoint being "it works now"...