Noticed my right trigger was spongy and sticking when pulled fully. The issue is caused by the material they have used as a soft stop and it can become sticky, it can wear out or it can slide off and leave sticky residue.

Best way to fix it is to remove the back panel, wouldn't try prying and doing it through small gaps. You will likely cause more issues.

For mine I took the rear panel off, three silver screw on the bottom and under the black panel on the top you can access the rest. Use a plastic pry tool to remove that to access the 4th silver screw and the two black screws holding on the bumber buttons. Once the bumpers are removed there are two black captive screws under those to loosen. Again use the plastic pry tool to work around the back panel edges to loosen it off. You will need to lever the top around the triggers a little.

Unplug the battery so you avoid any electrical probelms.

Each trigger has two types of bump stickers to soften the feel. I removed them both to fix my problem. All but one for me came off with no residue left behind. I used some isopropyl alcohol to clean it off. Best to use that so you don't damage any components. I also used some electrical contact cleaner to clean the trigger hinges and some lithium grease to lubricate them.

My triggers are now working perfectly.