-snip-
Thank you for your help. I entered the command
rescanblockchain and I got this : "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height. (code -1)"
Conclusion, I need to open the wallet.dat file with the good Bitcoin Core client... And I can't find it

That was the "
prune block storage" setting that I was talking about in my first reply.
You may stop the sync process now and disable the said setting; or if disabling isn't possible due to storage issue, only restart the sync once the target wallet is already loaded.
Read that post for more info.
But you know what is worst? I think that actually the Bitcoin Core 25 cannot open my 2011 wallet.dat file... I'm sorry to have misled you.
(I was misleading because of the text at the bottom of the video "sync with the network...3 years and 27 weeks" which made me think that the software use my file to sync it with the blockchain (while it's not)).
-snip-
The error message which appear in the window : "Wallet file verification failed. "C:/Users/imwon/AppData/Roaming/Bitcoin/wallets/my old wallet 2011/wallet.dat is corrupted. Try the tool bitcoin-wallet to fix it or restore a backup."
That error has nothing to do with the Bitcoin Core version since old wallets can still be loaded to the latest version without issues.
Bitcoin Core simply detected that it's corrupted.
As per the message, you can try to use bitcoin-wallet tool to salvage "
a copy" of it. (
make sure to keep an original backup)
Here's the instructions for Windows:
Try Bitcoin Core's bitcoin-wallet tool's "
salvage".
"
bitcoin-wallet" is in the "
bin" folder inside Bitcoin Core's installation directory (
where bitcoind and bitcoin-cli are located).
To use it, open Terminal,
cd to the directory where bitcoin-wallet is.
Then use the command (
provide the full path to the wallet.dat file):
bitcoin-wallet --wallet="E:\Folder\wallet.dat" salvage
It wont return with any response (
unless it failed) but you will see a backup file (
wallet.dat.xxxxx.bak) where the wallet.dat is located.
The new wallet.dat is the "
salvaged" wallet.
Notes: Depending on the binary, bitcoin wallet tool can be in "
daemon" folder instead of "
bin".
To expand some steps; "
cd" means "
change directory", here's an example to cd:
cd "C:\Program Files\Bitcoin\daemon"