As stated elsewhere here, go to your mom's banks and financial advisors, if any, and get their paperwork done for POA. They likely will not accept yours.
Your POA will do for many things but as AlvaDeer pointed out some financial institutions, especially the government, requires more paperwork. In addition, your POA doesn't work for medical information. You will need HIPPA release forms and a Medical POA. Every now and then you'll be surprised by something that should be easy but that won't be. If you run into a roadblock I've found most people will try to help you solve the immediate problem. Currently I'm in a change of address hell with the Defense Finance and Accounting system because of the Covid lockdown but the person at DFA did manage to work through my immediate problem to get a required bit of paperwork even though we'll need to wait until after I can get into the same room with my dad to make a permanent fix. I've also found that it is very helpful to keep a PDF copy of my POA and my medical POA and my dad's living will, etc on my phone and I have a password protected folder with all his paperwork on-line. During a hospital stay they wanted copies of my POA, etc and I was able to just pull them up and email them to the hospital right then. Otherwise I'd have had to go home and find the papers, copy them, and bring them back.
Hopefully this is a well written POA. If so you will do fine in most places. IRS doesn't accept POA; there are special forms you have to get to do taxes, sign for taxes and etc. Also Social Security doesn't accept POA; you would become a "representative payee" if you have to do that. Basically you are going to find out as you go along what you need with individual entities. My bro's life was simple but I spent year one after taking over waiting on the phone for help. I wish you good luck. Keep a diary and meticulous records of expenditure, transfers, assets and paid bills. Keep receipts for everything. After a year my wine-box file box for my bro was VERY full of folders. There is a lot to learn in this. Research; look for books that will help you. Do not waste time speaking with "tellers" and "phone folks" and get to the "top" as quickly as you can.Make appointments with bankers in the interest of doing that.
Do not waste time speaking with "tellers" and "phone folks" and get to the "top" as quickly as you can.Make appointments with bankers in the interest of doing that.