change in gas and temp gauges

The wild needle swings are a symptom of failing mechanical limiter but I can't say I've seen similar from a solid-state regulator. The little 7405 chip for example Amazon product ASIN B08YNNBYB7 will output 5.2 to 5.4 volts with input anywhere between 9 and 35 volts. The output will climb as they overheat though. The heatsink and the transference paste between the chip and heatsink are players. The thing is, they don't get goofy and/or continue to function half assed. They just die.
I'll lay my coin on a failing temp gauge. Pull the connector off that sender and see does the fuel gauge go back to proper responses.