It’s normal to be annoyed, I get annoyed when my mil tries to interfere when I’m teaching my kid/when my kid falls or cries. For my case, I’ll always ask them to stay away (even my husband) and not just take baby away.
Putting helping hand or love aside, outsiders should always allow the parents to handle their baby first until they ask for help.
It might be because they always give in to baby hence baby sees them as “angels”. It’s human nature that we always prefer someone who always gives in to us. Spend more time with LO, build up the bond. Ultimately end of the day, you are the mother and no one can break that bond.