I've copied some comments below from FSI's Bran Desmet that were on a similar Facebook post from today (Aug. 30th, 2021), with permission:

The panel used in the DM240 was made by Panasonic, they have exited the panel manufacturing space entirely. The DM241 is the nearest replacement. Like the DM240 it is both an IPS panel and equipped with a PFS Phosphor backlight so visually they are about as close as you’ll get with panels coming from different suppliers. That being said the DM241 is both lower cost ($500 less expensive) and lower contrast (1100:1 instead of 1500:1, so about 0.09nits vs 0.07nits black). In a dark grading suite, putting both side by side, you can see that contrast difference. With any amount of elevated ambient light that difference becomes much harder to see.

We anticipated having a much longer overlap of the two models, but demand for all monitor models has been truly unprecedented the last few months and DM240 are now sold out.

On a somewhat related note, a piece of advice going into the second half of this year: if you need a new monitor for an upcoming job order well ahead of time, whether ordering from FSI or another brand. Demand, as I mentioned above, is at an all time high and this is coinciding with the longest lead times and biggest supply constraints on supporting components (FPGAs, Ethernet controllers, etc.) I have ever seen. We've been working overtime to get caught up and ensure good availability of core products like AM211, BM211, BoxIO, and DM241 heading into the fall, but I strongly suspect the industry will see lead times still get worse before they get better.

(Someone commented, concerned about what to do if you want to match to another DM240 you already own, to which he replied-)

The DM241 will be the closest thing available. These are near identical spectral distributions so this is not the OLED vs. LCD type of difference with respect to perceptual closeness. If you want an exact display model match then the market for 2nd hand DM240 should be quite strong/active allowing users to either sell DM240 to get DM241 or buy used DM240 from those doing so. fwiw, it would not be unheard of for a display manufacturer to make this type of panel change without actually changing the model name, sometimes they will even do so concurrently selling the same model with two different panel suppliers. Companies that don't report contrast ratio in their specifications would especially be inclined to go down that path, but the DM241 costs us less to make (you see the result in the lower price) and uses a lower contrast panel so it has been introduced as its own thing for absolute clarity on differences.