Yeah, writing a lot of data while it updates is true for Bitdefender and every other product that is using BD signature. Updating in the morning, I mean if you haven't updated it in a while, might make BD write 600-800 MB data on the update. On other updates throughout the day, it'll be on average 400 MB I think. BD releases signature 5-6 times a day if I'm not wrong.
But I have to say even ESET writes about 400 MB data on each update, and their updating frequency is also similar. ESET also have streaming/pico updates which downloads 1 KB update file every 10 minutes. But of course this doesn't add anything. MD about 210 MB and Kaspersky 170 on average. But MD updates once a day by default, and Kaspersky don't seem to release updates often throughout the day (its log may fool you).
So anyway, for SSD users on PC, turning off hibernation is a better way to reduce some writes on the disk. My hibernate file size is just over 5 GB. Yours may vary. Turning it off is recommended unless you are using a laptop/HDD. I don't fully understand how to evaluate this hibernate file writes. Does it only writes data to it when you shutdown? Or some data is also written throughout the day? I never tested it, but looks like at least I'm reducing 10 GB data writes every single day since I usually turn off my PC twice a day (correct me if I'm wrong).
Moving browsers cache folder to a HDD is also a smart way to reduce some writes on SSD if you watch a lot of videos on your device. I browse YouTube quite a lot, so it helps.
So, everyone in general including anyone using BD/BD based products can follow this method to reduce disk writes on a SSD.