On the 15th of December 2021 they filed with the SEC in the build up to IPOing, at that time the rumours were they'd be looking for a $15Bn valuation. At that time, SNAP was worth about 60Bn, TWTR 40Bn (a notoriously shitty stock), Facebook 900Bn. SNAP is down about 60% since then, Meta is down 75%, and TWTR is out of whack because of the acquisition. So basically they missed their chance. They could IPO today, but they'd be selling reddit
very cheap, and they'd also be putting it under huge pressure since every other social media company is in the process of doing a huge round of layoffs so reddit would immediately need to start looking at their cost structure.
There's a couple reasons why it's so bad. Firstly, everyone's expecting a recession, so advertising budgets are getting cut and that's going to tank Reddit's revenue stream (which is already weak) and secondly, a high interest rate environment means that all that future growth has to be discounted back to a much lower net present value. It's also just in a bad place narratively, none of the small scale social media sites are doing well revenue wise, and Tiktok is eating their lunches anyway.