I do not see anything suspicious in this, even though we know nothing about the person's history. They may have been under intense pressure at work, in financial difficulty, just had a relationship breakdown, etc, making them feeling very low.
A job as a nursing assistant - not a nurse as has been referred to on occasion, but as implied by title, an assistant to the nursing staff; while having undergone training and exams, it is not same level as a qualified nurse - would have no doubt brought its own pressures, with Christmas ahead and perhaps through Covid/work/money not being able to spend time at home in Czech, could all have built up to feeling it was a very bleak time ahead. That she also tried to contact them in the hours after disappearing, I think is indicative.
Where she was found, if indeed it was suicide, the place is not unusual. Almost every case I have followed this year of a suicide, the location was away from home, in an open, but secluded space, and often with an expanse of water involved.
I can easily see why she may not have been spotted. We are so used to seeing homeless in different places, that we are now just immune and pass by like nothing out of the ordinary. Anyone passing might have mistaken her for one, or thought just a pile of clothes left, and not bothered to investigate further.