Is it true that many companies drag out hiring when they’ve already picked someone?

I recently interviewed for a senior role and had a pretty odd experience. Here’s what happened:

• One of the interviewers didn’t show up: Initially the interview was scheduled with 3 people (a senior PM and two engineering managers/directors), but only the PM and one engineer showed up.
• The interview felt very one-sided: I asked a lot of detailed questions about their design system and team structure. They answered, but there wasn’t much engagement or follow-up. Most of the time, they just talked about their product vision.
• No real discussion about my fit: I briefly did my elevator pitch, design process, and a couple of past projects, but they didn’t ask many follow-up questions or seem genuinely interested in assessing my fit for the role. I felt like I was the interviewer instead of being interviewed.
• The role has been open for a long time: The position has been posted since May. With so many talented designers available in the current job market, why hasn’t it been filled yet?

All of this made me feel like they might’ve already chosen a candidate and this interview with me was just a formality. I was truly excited about the job opportunity and took a lot of time to prepare for this 4th round, the previous interview with the design director was really good too, but after this experience, I’m not sure how I should feel anymore...

Is it common for companies to drag out hiring even when they’ve already locked in someone?
Or is this just a case of engineers not being great at interviews? Or am I just overthinking??

I’m 99% sure I’ll get a rejection email soon, but honestly, the vibe of the interview didn’t feel promising anyway. Has anyone else been through something like this?