This weekend, it was discovered that some advertisers were deliberately misspelling BITCOIN as BlTC0lN to evade the ban.
The i and 0 being swapped for a similarly looking lower-case L and 0 in the cited case. Facebook is said to have begun investigating the issue once it was brought to their attention.
"This policy is intentionally broad while we work to better detect deceptive and misleading advertising practices, and enforcement will begin to ramp up across our platforms including Facebook, Audience Network and Instagram. We will revisit this policy and how we enforce it as our signals improve." Facebook wrote, when it first introduced the policy, further noting that "We understand that we may not catch every ad that should be removed under this new policy, and encourage our community to report content that violates our Advertising Policies. People can report any ad on Facebook by clicking on the upper right-hand corner of the ad."
Ads like this come under what Facebook refers to in the latter half of the extract, and would most likely help provide data the social network would use to craft its cryptocurrency advertising policy in the months to come.
Substituting letters for alternate characters to bypass a ban or trick hapless users is a stock trick of scammers. In 2017, this was highlighted by researchers, with someone easily spoofing the Apple dot com domain name by substituting one of the Unicode characters for a Cyrillic one.
Most ironically, the existence of unscrupulous players like this bolsters Facebook's case for a temporary stay of advertising pending a fuller review.