Not made a claim sice SPG was merged with Marriott and just learned. >
Rates on auction websites, on sites that do not disclose the hotel brand until the reservation is completed (i.e., Priceline and Hotwire), on sites that require a login or specific credit card to view or book, or on sites that don’t provide an immediate confirmation (e.g., an “on request” rate) are not accepted. Pre-paid, advance purchase, or non-refundable rates on Qunar, eLong, Meituan Travel, Ctrip/Trip.com, Ctrip/Trip.com affiliate sites, or Fliggy are not eligible. Any rates on WeChat are not eligible.

Consens Marriott knows that TRIP.com is cheaper ! So if you plan to book and BRG a trip.com rate, better reserve a refundable rate on Marriott first, otherwise them catch you and you NOT get the BRG and also can't cancel ( for free ) the rate you confirmed with Marriott. This is a bad change comparing with SPG ! With SPG only the rates on auction websites didn't count, or the ones which not confirmed and had to requested first.....Like this now, only the higher standard rates are eligible for BRG....