I found a decision by the FIDE Ethics Comission (FEC) that is interesting in relation with this question. In this case (Decision 2/2020), two players were observed talking during a competition. Afterwards, one of the players wrote on her scoresheet "Draw or I win?" There were also calculations of the tournament standing and the distribution of prize-money. The arbiter forfeited both players and they were declared ineligible for prize money in the tournament. They were also banned from FIDE rated events by the FEC for 24 months (the last six months suspended and serving as probationary period). The decision arguments the following (emphasis added by me):
10.3. The concept of match fixing in chess may be described as an arrangement between the parties with the aim of agreeing the outcome of the game in violation of the accepted principles of sportsmanship and fair competition, often involving deliberate underperforming by one of the parties.
10.4. When contemplating the concept of match fixing, the EDC Chamber notes that arranged draws are widely known to occur in both national and international events. The reasons for an arranged draw may vary. For example, both of the players may want to save energy for later games, or may be satisfied with their tournament standing and are therefore averse to taking risks. There is an argument for regarding arranged draws as contrary to the concept of sportsmanship and fair competition as it takes away the competitive aspect already before the start of the game. The EDC Chamber does not however find arranged draws as unacceptable match fixing per se, primarily due to the fact that chess players are allowed under the Rules of Chess (art 220.127.116.11) to propose and agree to a draw, admittedly only during the course of the game, and none of the parties thereby agree to lose the game.
10.5 There are situations where arranged draws may be in violation of the concept of sportsmanship and fair competition to such an extent that it would qualify as match fixing. One example is where one of the players is offered some kind of remuneration to agree to a draw.
Thus, to be considered as bad sportmanship, the decision to lose should be deliberate (and not the result of ineptitude, as mentioned by @Brian Towers), specially if there is some kind of remuneration or benefit for one or both players. That would require for the arbiter to have evidence of the said remuneration or benefit or that there was an agreement between the players.
For example, in another case investigated by the Catalan Federation of Chess (Resolution 20/2019 and Appeal Resolution 5/2019, in Catalan) a higher rated player lost to a lower rated player. However, the lower rated player had already previously resigned and agreed to continue the game. By winning the game, the lower rated player ended first in his category and won a prize of 40 €. The arbiter had observed the higher rated player had had considerable advantage during the game. However, he could only act when he obtained (some days later) a WhatsApp conversation where the higher rated player said he had sold the point for 5 €. When asked by the arbiter some time later, the lower rated player recognized the facts and the arbiter denounced the facts. The lower rated player was suspended and banned from participating in Catalan Chess Federation competitions for one year and was requested to return the prize. The higher rated player did not have a Catalan Federation license and was banned from participating in Catalan Chess Federation competitions for two years.