I'm more interested in where!
There is not a single resort called Bulgaria. there is a long Black Sea coast stretching from Romania to Turkey, and a lot of Bulgaria is inland to the borders with Greece, Macedonia and Serbia.
The name Lotus or Lotos is merely a transliteration of the Cyrillic Lotos (I don't have Cyrillic letters loaded on this PC), and thus both derivations are correct and interchangeable.
On the internet under Hotel Lotos there are hotels in the Riviera Resort, Balchik, Golden sands. and Sunny Beach.
Under Hotel Lotus there is one at Sunny Beach only, but this hotel appears under both variations of the name. The owners were backing it both ways!
We have in our reviews the Hotel Lotos in Golden Sands which is a correct name in the right place.
If the Hotel Lotos being asked for is in Golden Sands, we've got one review.
The names of Bulgarian hotels can drive you nuts, have you noticed?! They vary from brochure to brochure, and website to website.
Peter