Here in Belgium, or I guess other EU counties aswel, there's a limit to deposit cash before it gets suspicious. I don't know how much actually.
I'm not sure every bank verifies these transactions, perhaps it depends on the person at the desk.
But I know they ask regularly.
The best thing is to inform how much you can deposit legally per week or month, and add this amount to your account. After a while you have everything on it...
The banks also ask these questions now to people who do crypto transactions and suddenly transfer a lot of money from their crypto exchange platforms to their bank. Also money from Paypal is seen as a "foreign bank". You could better leave it there and pay online from that account.
It was strictly problem with deposit of cash. No such problems in Canada, but dude in Liege BNP Pariba Fartis fricked out after seeing less than 10K USD in cash. From person who just came under full police check and living permit to Belgium.
Here in Belgium, banks are stuck in 19 century.
We had to transfer money from one Belgium bank to another for mortgage/down payment.
Instead of transfering, dude put us on hold and after half-our refused to do so.
Simply because none was aware how money gets into Belgium banks first.
Dude told me - you have account in Netherlands (I do not), no transfer from our Belgium bank to another Belgium bank, increase transfer amount - do yourself. He forgot to told me in Belgium if you increase amount for on-line transferring, it takes one %&#$G week. And they had no clue about intermediary banks in Netherlands for international transfers.
But I knew it is Belgium banks, I had backup appointment in Flanders.
We came and money were transferred instantly, two hours before deadline and losing 20K Euro as deposit...
I'm holding the record in Belgium for getting mortgage within year and half after arrival under A type permit to stay.
It was endless fight with clueless bunch in Belgium banks and brokerage agencies, until one day I've got local mortgage broker recommended. He it is the only person who was able to make it for me. But still, endless fight with endless demands, which were irrelevant for buying property, but keeps unemployment rate in Belgium low.