Decided to still collapse newlines...

and to solve the offset issue by replacing excessive newlines with
the zero-width space unicode character.

spec/messages.js

@@ -626,7 +626,10 @@ describe("A Chat Message", function () {
             </message>`);
         _converse.connection._dataRecv(mock.createRequest(stanza));
         await new Promise(resolve => view.model.messages.once('rendered', resolve));
-        expect(view.content.querySelector('converse-chat-message:last-child .chat-msg__text').innerHTML.replace(/<!---->/g, '')).toBe('Hey\nHave you heard\n\n\nthe news?\nhttps://conversejs.org');
+        await u.waitUntil(() => {
+            const text = view.content.querySelector('converse-chat-message:last-child .chat-msg__text').innerHTML.replace(/<!---->/g, '');
+            return text === 'Hey\nHave you heard\n\u200B\nthe news?\n<a target="_blank" rel="noopener" href="https://conversejs.org/">https://conversejs.org</a>';
+        });
         done();
     }));
 

src/shared/message/text.js

@@ -8,6 +8,11 @@ import { html } from 'lit-html';
 const u = converse.env.utils;
 
 const isString = (s) => typeof s === 'string';
+
+// We don't render more than two line-breaks, replace extra line-breaks with
+// the zero-width whitespace character
+const collapseLineBreaks = text => text.replace(/\n\n+/g, m => `\n${"\u200B".repeat(m.length-2)}\n`);
+
 const tpl_mention_with_nick = (o) => html`<span class="mention mention--self badge badge-info">${o.mention}</span>`;
 const tpl_mention = (o) => html`<span class="mention">${o.mention}</span>`;
 
@@ -317,6 +322,6 @@ export class MessageText extends String {
                     ...list
                 ];
             });
-        return list.reduce((acc, i) => isString(i) ? [...acc, convertASCII2Emoji(i)] : [...acc, i], []);
+        return list.reduce((acc, i) => isString(i) ? [...acc, convertASCII2Emoji(collapseLineBreaks(i))] : [...acc, i], []);
     }
 }