If it works well, it's worth paying for
It is good that they keep a free tier available, some people obviously don't have that much use for audio transcription. But it is indeed perfectly normal that they adjust their offering to market conditions. Regardless of the desires of the investors, if they have a good product it would be a shame for the company to fold because they couldn't hold the demand and stay alive at the same time.
Let's just hope that they don't use servers in China.