Increase Allowance function transaction. Is this something to worry about? Contract can thus also decrease allowance and set to zero so basically blacklisting and unable to transfer?

I saw in Etherscan a transaction with the 'Increase allowance function. It seems suspicious to me, then probably decrease allowance function also is possible. And that leaves the door open for somebody decreasing allowance to zero for example, basically blacklisting any address they want?

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Any input on this? cheers!