Greetings.
Team Switched have recently changed their Sans design, and it seems they have received a lot of backlash from this move.
From the get-go, I would like to clarify:
I am not attacking any specific group of people, negating others’ opinions, or blindly saying TSUS is the true replacement of Underswap and no other Underswap is allowed to exist.
I am merely defending Team Switched’s Underswap choices, and how it does not matter if they change their designs to match their canons rather than keeping with the commonly accepted version of Underswap.

Okay. Here we go.

Team Switched do not want to rename their AU, as it is still Underswap. If it contains the original character placements, it is still an interpretation of the original AU. Team Switched are also not trying to replace the version of Underswap most people know - hence why it is commonly referred to as Team Switched!Underswap rather than just “Underswap.”
To clarify, I will be referring to the commonly accepted version as “Classicswap” and Team Switched’s as “TS!US.”

PopcornPr1nce, the original creator of Underswap allows interpretations of his AU.

Evidence:

Now, TS!US does not swap personalities. Rather than keeping to the specifics of Undertale and changing the character placements, preserving the attitudes and actions - TS!US investigates what would happen if the characters preserved their personalities, but the events of the world around them changed, hence their different placements.

Now, some might say that that’s just Inverted Fate. It’s not.

Dorked - the original creator of Inverted Fate, created a detailed post as to why it’s not here.

Classicswap largely keeps the original canons, exact storyline and keeps the Papyrus replacement (Sans.) as an enthusiastic, energetic Royal Guard In Training but keeps his love for puns. The Sans replacement, (Papyrus,) is laid-back, knows about resets, is lazy, but still keeps part of his original personality like his enthusiasm for japes and puzzles. You can read more
about this in Demirramon’s extensive research around PopcornPr1nce’s canon Underswap here.

TL;DR, Team Switched swaps:

• Chara <-> Frisk

• Asgore <-> Toriel

• Asriel <-> MK

• Sans <-> Papyrus

• Undyne <-> Alphys

• Napstablook <-> Mettaton

• Grillby <-> Muffet

which are the crucial placements and canons needed for making it an interpretation of Underswap and not a separate AU, just like Classicswap.

Oh, and I am not attacking you if you like Blueberry Sans or any of the other “fanon” interpretations of Underswap, but this was the original creator’s stance on it:

(From the archives of the original underswapped.tumblr.com.)

Also, Team Switched have never had a public gofundme. Not sure where that rumour started.

• Sanes, Primus