There isn’t enough information in your question to be sure, but one common reason money leaves your wallet unexpectedly is theft. This means that someone else has the private key to the receiving address in the first transaction.
This may be because you had an online friend or assistant to guide you through the initial process and selection of wallet software. Maybe this online friend wasn’t your friend and was intentionally deceiving you in order to steal money from you.
This may be because you downloaded maliciously modified software rather than genuine software. This happened to many Electrum wallet users a few years ago. The thief used the software’s functionality for malicious purposes by tricking people into downloading a malicious version from a website run by the thief.
This could be because the device you use to store your wallet software also uses it for other purposes, and at some point you downloaded some compromised software or software that opened a security hole for thieves to exploit.
Some red flags:
I was forced to join this platform by the company.
Being forced into unfamiliar processes is very common in fraud and theft cases.
The word platform suggests something other than a typical non-custodial wallet.
Bitcoin was specifically designed to allow one party to pay a second party without the services of a trusted third party, without any kind of business service acting as a trusted intermediary. Using a business to store your money is giving up one of the key benefits of Bitcoin, as its creator intended.
account
The transaction pattern suggests a typical non-custodial (self-custodial) wallet, but the use of the word account suggests some kind of online business service, i.e. some kind of custody arrangement.
It is common for criminals to confuse and embarrass their victims, which often causes their accounts of events to appear contradictory and confusing.
Other questions you might find helpful answered include: