There are electrical problems that can cause weak flippers, but mechanics have to be working perfectly before you should look into troubleshooting the electronics. (EDIT: Nope, you should clean the optos first, see below, thanks The_Pump_House!)

I would recommend getting a flipper rebuild kit:

https://www.marcospecialties.com/pinball-parts/WFLTRON-1L2R

Take the flipper assembly apart and replace anything that is dodgy.

There are so many mechanical problems that can cause flipper issues, and most of them require parts to fix.

Get the parts. Rebuild the flippers.

If you still are having problems, let us know!

Can’t argue with rebuild kit. New arm linkage, coil stop and coil sleeve are the most important parts

You could also make sure the wires are soldered securely to the lugs on the coil. And clean the contacts on the flipper switch in the cabinet (put rubbing alcohol on some thick paper like a business card and put it between the switch contacts and gently squeeze the switch and rub the contacts).

Do the most basic thing that costs zero dollars first.

Clean your flipper optos.

Open the coin door and enter the service menu. Go to switch tests. Push the flipper button and you will see 2 boxes light up on the DMD. Do they stay lit solid or are they flickering

exactly where I'd start.

Probably just needs a rebuild.

To access the flipper opto boards raise the playfield. The optos are small black
Plastic U shapes. Cleaning the inside of that U may fix your problem.

If this does not fix your problem swap the left and right flipper opto boards and see if the problem follows the board.

Might be connectors on the power driver board for the flippers. I'd look at those as well.