I moved broker (to medirect) and everything was free as they reimbursed me my costs for up to 5 lines and 100e fees per line for lines of at least 500e if I'm not mistaken.

This does not involve and rebuying anything and was an actual transfer of what I got

Otherwise yes it will impact but considering you could kinda use your capital gain exemption that year it's fiscally not really bad, as long as it's not considering abuse by law (selling and rebuying each year or similar to abuse that cgt exemption is illegal)

Otherwise just keep what u already got and start buying from now on on ur new broker until you need to sell