I've experienced the same thing when trying to process some members data, always failing I will the same spot since a few days. Last time it was because staff profiles were protected, but this time I couldn't get an idea on why this happens.
recent issues with some endpoints

I get the same response - some corruption of the endpoint data probably?
Best to report them as you come across them....

Response from Support:
Re: Error with API endpoints
Hello Tricky_Dicky,
I'm Bert from the Chess.com support team, and I wanted to address the report you recently filed.
Could you check now if you are still having this issue?
I checked on my end but it works fine when I click this https://api.chess.com/pub/player/sboorman/stats
Probably it's being rate limited (too many requests at short intervals)
Let us know how it goes.
Kind Regards,
- Ignored the Code 0 error
- Suggested rate limit despite no code 429
- Concentrated on this specific user endpoint instead of understanding that it's a DB internal error
- That specific endpoint works now so the problem has gone away.
- 6 day response time: From last monthly update - 'Average Time to First Response: 1 day, 5 hours'. I must be unlucky because I usually find it's about a week.

I don't know if it's really fixed for you, on my side I still have an error on this member:
https://www.chess.com/member/psp2010-> OK
api.chess.com/pub/player/psp2010-> OK
api.chess.com/pub/player/psp2010/matches-> error
{
"status": "error",
"message": "Internal Server Error"
}
I guess I'll open a ticket myself.

Yeah, working normally now....
https://api.chess.com/pub/player/sboorman/stats
But how many others are not?

I get a different error here: https://api.chess.com/pub/player/risdr/matches
{"code":0,"message":"An internal error has occurred. Please contact Chess.com Developer's Forum for further help https://www.chess.com/club/chess-com-developer-community ."}
That's a nice one

You couldn't make this up. Just got this
https://api.chess.com/pub/player/byebyebadman
"An internal error has occurred. Please contact Chess.com Developer's Forum for further help https://www.chess.com/club/chess-com-developer-community ."

yea Idk whats going on but when i try to analyze some masters games i get that error.
example endpoint: https://api.chess.com/pub/player/witty_alien/games/2022/10

and another two today
https://api.chess.com/pub/player/peace217
https://api.chess.com/pub/player/salosknight

Happy New Year to the Devs. Maybe fix some of the problems this coming year?
Here's another two
https://api.chess.com/pub/player/grahamcuthbert
https://api.chess.com/pub/player/aswwjm2000s

Today's internal DB failures
https://api.chess.com/pub/player/nobbytroy
https://api.chess.com/pub/player/sacbutt
https://api.chess.com/pub/player/b1galff

Hey! Thanks @Tricky_Dicky
I found your ticket that lead me to this forum. I just wanted to let you know that I am hitting these errors too with the recent ones you posted.
I'll amplify this issue and get some developers to take a closer look. Please keep posting any errors you come across as it does seem that some older ones are okay, and knowing which ones are hitting errors may help in tracking this down quicker.
It's not a big problem but recently getting internal errors from some end points
This is an example. There have been others.
https://api.chess.com/pub/player/sboorman/stats
Valid member with available stats.