Probably a bunch of little details, cables, tubes, speakers, misc guitar set-up stuff.
There’s lots of little trims and tweaks for Fender amps if you need just a little more clarity or veil, headroom or gain, etc.

First thing I’d do to get a little more high end extension out of any Fender is take the tube shields off.
Also, very important!!
Just went thru this with another post, but don’t put a bunch of extra cables and effects between the guitar and amp.
Just listen to the guitar and cable at input so you have some baseline or benchmark for keeping track of changes.
Try the tube shields off and get back to me .

Steve what type of tubes do you like?

The old ones were better. .
lol
Seriously, for the Fender amps either NOS RCA or GE in the preamp with an occasional Telefunken for phase inverter.
90% of the time anyway, that’ll do it.
I do use Mullard and Amperex as well, and there’s lots of rebranded tubes, Fischer could be Telefunken with a Fischer brand on it.
You can always check the bottom of the tube, if there’s a little square/diamond embossed into the glass in the middle of the pins, that’s a Telefunken regardless of the paint.

For output tubes, same deal, RCA and GE are great, but I use plenty of the small bottle JAN Phillips too.
I still use the big bottle Sylvania STR415 Mesa Boogie tubes occasionally too for “big amps” 4x6L6 like Dual Showman for bass.
Kind of a specialty tube for me now, big, powerful, cool running, rugged.

The trick for the old output tubes with the Fender amps is you can buy “broken” tubes if you find any.
The broken part is the locater pin, without which you risk smoking your amp by plugging the tube in wrong.

The fix is leave the amp on standby STANDBY

then just keep rotating the tube and plugging it in until the heaters light.
There’s only one orientation the tube will work in, and when it lights up, you got it!

anyway, if you see “broken locater pin(s) in the description, don’t worry, take the discount, use your standby switch etc.